/Engine/Plugins/FX/Niagara/Source/Niagara/Classes/NiagaraEmitterInstance.h
Calculate total number of spawned particles from events; these all come from event handler script with the SpawnedParticles execution mode We get the counts ahead of event processing time so we only have to allocate new particles once TODO: augment for multiple spawning event scripts
uint32 CalculateEventSpawnCount ( const [FNiagaraEventScriptProperties](API\Plugins\Niagara\FNiagaraEventScriptProperties) & EventHandlerProps, [TArray](API\Runtime\Core\Containers\TArray)< int32, TInlineAllocator< 16 >> & EventSpawnCounts, [FNiagaraDataSet](API\Plugins\Niagara\FNiagaraDataSet) * EventSet )